As shown in FIG. 4, a typical stator of a universal motor consists of a plurality of single piece laminations stacked together. The stator comprises a yoke 14 and a pair of opposing poles 16 extending from an inner surface 15 of the yoke 14 via a neck 18. Receiving spaces 20 are formed between the poles 16 and the yoke 14. Windings 22 are wound around the poles 16 in the receiving spaces to locate about the neck. However, the winding is loosely wound as the force applied to the wires during winding is not sufficient to produce a tight winding in order to avoid breaking of the wires. The loose winding cannot be arranged to extend outside of the receiving space as it is easy for turns of the winding to fall into the gap between the pole and the rotor causing failure of the motor. Thus, the winding is limited by the length of the poles 16.
One known option to overcome the above problem is pre-forming the winding 22 and then mounting the pre-formed winding to the poles 16 of the stator core. However, the opening of the winding 22 should be greater than the width of the poles such that the poles are capable of extending through the opening of the winding 22 without deformation to allow the winding to be mounted to the poles. Thus, the winding 22 is not fixed relative to the stator core after assembly. Another known option, as shown in U.S. Pat. No. 7,546,672, is to pre-form the winding 22 with an opening equal to the width of the neck. During mounting of the windings to the stator core, the poles 16 are squeezed. After the windings are mounted to the stator core, the poles 16 are deformed to return to their original shape whereby the poles retain the windings 22 in the receiving spaces. However, the poles are deformed twice and the process is therefore complicated.